Photographic reversal process of producing dye images without reexposure



Patented Feb. 16, 1943 PHOTOGRAPHIC REVEBSAL PROCESS OF PRODUCING DYE IMAGES WITHOUT RE- axrosunr:

Emery Meschter, Milltown, N. 1., assignor, by mesne assignments, to E. I. du Pont de Nemours & Company, Wilmington, DeL, a corporation of Delaware No Drawing. Application September 19, 1939, Serial No. 295,687

Claims.

This invention relates to photographic proc-v esses. More particularly it relates to photographic reversal processes involving the production of dyestufi images. Still-more particularly it relates to processes for obtaining direct posiable for processing sub-standard size film.

Other objects include the provision of a blackand-white reversal process of increased dye density which involves a minimum number of steps and a general advance in the art.

The above objects are accomplished by the following invention which comprises the use of an aqueous reducing composition containing an aromatic polyamino developing agent containing at least one unsubstituted amino group and a nitrogenous base free from negative groups and hydroxyl groups attached to carbon, in the presence of a black color former for developing residual or reversed images.

In a more limited sense the invention comprises the formation of black and white reversed dyestufi images by the use of an aqueous reducing bath containing an arylene diamino photographic developing agent and a, nitrogenous base free from negative groups and hydroxyl groups attached to carbon, in the presence of a black color-former for developing the residual or reversed image.

In a still more limited sense the invention comprises the formation of black and white reversed dyestufi images by the use of an aqueous reducing bath containing an arylene diamino developing agent free from nuclear hydroxyl groups and a nitrogenous base free from negative groups and hydroxyl groups attached to carbon capable of energizing said developing agent so that it no longer distinguishes between exposed and unexposed silver halides in its reducing action.

' fall within numerous classes.

The energizing agents which change aromatic polyamino developing agents containing at least one unsubstituted amino group and especially those free from negative and hydroxyl groups do not fall into any one specific class of bases but The operative nitrogenous bases as previously stated are free from negative groups such as halogen atoms, e. g. Cl, Br: nitro, $03M, COOM wherein M is H or a metal, and hydroxyl groups, attached to carbon. The bases which are water soluble or can be readily dispersed in aqueous systems'are most efiective. Bases which do not have the above constitution, for example, the alkylol amines, e. g. mono-, diand tri-ethanol amines, do not function in the reducing solutions of the present invention.

An important class of nitrogenous bases which are organic amines may be represented by the general formula:

wherein each R1, Ra, Ra and R4 may be hydrogen,

alkyl, cycloalkyl, aryl, aralkyl, or wherein two Rs may represent a divalent polymethylene hydrocarbon radical or three R's may represent a cyclic trivalent hydrocarbon radical such as a polymethenyl radical which with the nitrogen atom, forms an N-heterocyclic nucleus.

' Another important class of compounds which wherein each R1, Ra, Re and R4 may be hydrogen, alkyl, cycloalkyl, aryl, aralkyl, and further characterized in that the methylene groups may be substituted by allsyl, cycloalkyl, aryl and aralkyl groups and at least one of the methylene groups may be substituted by amino groups, and n is l to 8.

As examples of suitable alkyl groups which may be present in each or the above formulae mention is made of methyl, ethyl, propyl, isopropyl, n-butyl, tertiary butyl, pentyl, lsopentyl, octyl, doolecyl, tetradecyl, octadeoyl. Suitable cycloalkyl radicals include cyclobutyl, cyclopentyl, and cyclohexyl. Suitable aryl radicals include phenyl, tolyl, s-naphthyl, p naphthyl. etc. Among the useful aralkyl radicals may be men tioned benzyl, 2-methyl benzyl, naphthyl methyl, etc.

The objects are attained in a refinement oi the invention by the preparation of reducing compositions, particularly aqueous baths containing an N-diallryl phenylene diamine of the gen eral formula:

R H 12/ \H or a water soluble salt thereof, wherein R and R are the same or diiierent lower alkyl radicals, e. g. methyl and ethyl: and a nitrogenous base free from negative groups and hydroxyl [groups and falling within one oi the formulae ll, 2, and 3.

It has been found that reducing solutions of the above type produce excellent black-and-white reversed dyestuil imases ii a black color former is present during the reduction step. The color= former may be present in the emulsion layer or in the aqueous reducing bath, but is prefer= ably in the layer.

Because of the activity of the reducing baths, it is not necessary to re-expose the photographic element after the first development or formation of the negative images. The elimination of this step presents a. distinct advantage in that it saves processing time, cuts down the size of the processing apparatus, etc.

Due to the energetic dye-producing action of the reducers shown above, the density of dye image is considerably greater, per density of silver produced, than with ordinary color-forming developers. Accordingly, the amount of silver halides need not be as great to produce a satisfactory dye density and thus the total coating weight of the emulsion layer can be materially reduced over that required for films to be processed by ordinary reversal processes.

The invention will be further illustrated but color former per kilogram of emulsion is processed after exposure as follows:

1. Develop 8 minutes in a metol-hydroquinone positive type developer.

is not intended to be limited by the following examples:

Example I A film element provided with a panchromatized silver halide emulsion layer coating of about 80 milligrams p r 100 square centimeters and con-= tai'nintt about grams of p-naphthol as a black 5 2. Wash.

3. Reduce residual silver salts by treatment for 12 minutes in:

2-amino-5-diethylaminotoluene-2HC1 m grams" 6 B-dimethylaminoethylamine cc Sodium sulflte, anhy "grams" Water to ...liter 1 4. Wash. 15 5. Bleach silver imases in 4% alkaline otas- -sium ferricyanide.

6. Wash. '1. Fix in:

Sodium thiosulfate, 'IHeO grams 300 20 Potassium alum do 20 Water to liter- 1 8. Wash and dry.

In place of the specific reducing baths set forth above in step 8 may be substituted any one of the followlnz baths with equally good results.

Earth A p-amino-N-diethylanillne "grams" 2 so Ammonium hydroxide, cone cc 26 Eiodium sulfite, enhy "grams" 2 Water to liter 1 Bath B p-aminodiethylaniline "grams" 2 Hexamethylenediamine mee 15 Sodium sulfite, anhy "grams" 3 Water to liter l 6 Bath L p aminodiethylanilinis grams 3 Ammonium hydroxide, conc cc 30 Sodium carbonate, anhy "grams" 2 Water to liter 1 5 Bath. B I

p-aminodiethylanlline grams 3 ifiedimethylaminoethylamine cc 20 Sodium suliite, anhy grams 3 Water to liter..,. 1

Bath 5? p-eminodiethylaniline grams 2 Eiperikline cc 25 Sodium sultlte, anhy "grams-.. 2

Water to "liter... 1

Bath F 2-amlno-5-diethylamino-to1uene grams- 5 w Trimethylbenzyl-ammonium hydroxide cc 20 Sodium sulflte,anhy grams 5 Water to liter 1 Bath G 4:4-diaminodiphenylamine "grams" 4 Hexamethylenediamine cc 10 Sodium sulflte, anhy grams 2 Water to..--. liter 1 7o Bath H 1:4-dlaminonaphthalene "grams" 3 Dimethylcyclohexylamine cc 30 Sodium sulflte, anhy "grams" 3 Water to "liter..- 1

Bath I to which add 4-diethylamino-l-naphthylamine grams 5 2 5 di h lb 1 Gram: B-dimethylaminoethylamine cc 20 i 1 enzoxazqe 10o Sodium sulflte, anhy grams-- 5 y ace "T Water to 1 In place of 2-5-dimethylbenzoxazole, which Bath J produces a bluish-black image, 2-methylbenzoxazole and 2-5-dlmethylbenzo-thiazole can be pamind1bty1a1 mme 3 used to produce brownish-black images. Simi- Hexamethylenedmnflne larly, other reducing baths, e. g. A. or C to K m sumte anhy 2 may be resorted to with similar results. Water to 1 The low coating weight of emulsion on sensi- Bath K tizzdmoapers has, in the past, seriously militated aminodiet lamnne rams" I 3 as t their successful use in reversal processes. %rimethylbefigyl ammonium hydroxigeuccn 25 The characteristic of the dye-forming reducers sodium sulfite, anhy "grams" 3 to produce extremely heavy deposits of dye-im- Water ton 1 age for relatively low density of silver deposits, now makes it possible to employ the economical Example H projection papers for rapid reversal processes To one kilogram of panchromatized silver gelatyielding positive prints. ino bromide emulsion are added grams of a 20 The color formers, as previously stated, may mixture composed of 9 parts by weight of mbe placed in the aqueous baths instead of emuldodecylaminophenyl-hydroxynaphtho-thiazole sion with similar results. They may be added sulfonic acid and 1 part by weight of l-(min a solvent such as ethyl or methyl alcohol or stearoyl-aminophenyD- 3 methyl -5-pyrazolone acetone to which may be added alkali, e. g. sodissolved in sodium hydroxide-alcohol solution. dium hydroxide. A 90 mg. coating of this neutral color-forming In place of the specific black color former set emulsion is coated on subbed cellulose acetate forth in the previous example other black color film base, exposed and processed as described formers may be substituted. Thus suitable addi. under Example I. Dye-forming bath B is used tional blank color-formers include N-dodecylto reduce the reversed image in step 3 of the 1:2-hydroxy-naphthoic acid-2-amino carbazole, process. meta-dodecoylaminophenyl hydroxynaphtho- The simplified reversal process introduced by thiazole sulfonic acid mixed with 10% of 1(mthe present invention also makes possible an stearoylaminophenyl)-3-methyl-5 pyrazolone; economical method for the production of en- 4-(a-hydroxynaphthoyl)4' (p nitro-benzoyllarged black and white prints from colored transacetyl) di-chloro-benzidide (for emulsions) for parencies. Recently several commercial films developer use:beta-naphthol diketohydrinhave become available for the production of coldene, 2-5-dimethylbenzoxazole, 2-methyl-benored transparencies. It is ofttimes desirable to zoxazole, 2-5-dimethylbenzothiazole. produce enlarged prints from such positive color 40 In place of the aromatic polyamino developing transparencies but the required process of makagents free from nuclear hydroxyl groups set ing an intermediate negative and projectionforth in the above examples, may be substituted printing from this is costly if only a few' prints in whole or in part one or more other specific are desired. The other method involving the compounds. Suitable additional compounds of reversal of printing paper by known methods does this type, which are known photographic develnot yield satisfactory results. The above disoping agents include: advantages are overcome by this invention. The i b following example illustrates this embodiment enzene hereof 2:5-diam1notoluene p-Aminomethyl aniline Example In p-Aminoethyl aniline A silver chloro-bromide or chloride projection p-Aminodimethyl aniline paper is bathed in a solution composed of 8 millip-Aminodiethyl aniline grams of pinacyanol, C. I. 808, and 6 milligrams p-Aminodibutyl aniline of pinafiavol, C. 1. 808A dissolved in a mixture 2-Amino-5-diethylaminotoluene of 650 cc. water and 350 cc. ethyl alcohol and 2:5-diaminomethoxybenzene containing 15 drops of concentratediammonium l-amino-4-phenylaminoacetic acid hydroxide. After sensitizing for 4 minutes at 4:4'-diaminodiphenylamine 70 F., the paper is washed for five minutes in 2:4-diaminodiphenylamine running water and then dried. The colored posl- 4-amino-N-phenylpiperidine tive transparency is then enlarged directly on 4-amino-N-phenylmorpholine to the sensitized projection paper. The print is 1:4-diamlnonaphthalene developed 1 to 3 minutes in 4-aminodiethyl-l-naphthylamine sodium sulfite grams p-Am phenyl-ll4-llaphthalenediamlne Hyqmqlimme and their water soluble salts, e. g. chloride, 5111. Bone f -7 fate, acetate, oxalate, etc. potassmm brnmfde Similarly, other basic compounds which cause Sodmm hydroxlde the above developing agents to become overall Water to 1 reducing agents may be substituted in whole or then washed. The reversed image is reduced by in part for the specific bases set forth above. treatment for 3-5 minutes in Thus, one or more of the following may be used: 2-amino-5-diethylamino-toluene grams 5 Lower alkylamines such as mono-, diand tri- Trimethyl-benzyl ammonium hydroxide 'cc 20 methyl, ethyl, n-propyl, n-butyl, etc. amines. Sodium sulfite, anhydride grams 8 which contain no negative groups, especially Water to -liter 1 hydroxyl groups in the hydrocarbon radicals;

straight and branched chain alkyl monoand poly-amines free from nuclear negative, especially hydroxy groups, e. g. ethylenediamine, hexamethylene diamine, triamino-propane, B- dimethylamino ethylamine, n-propyl-amyl hexylamine, tri-n-amylamine, di-iso-amylamine, cyclic and heterocyclic amines, e, g. piperidine. methylpiperidine, ethylpiperidine, piperazine, N- dimethylcyclohexylamine, N ethyl N methyl cyclohexylamine, n-octyl-pyridinium hydroxide; quaternary n-hydroxides free from nuclear substituted negative groups especially hydroxyl groups, e. g.

Trimethylbenzylammonium hydroxide Tetramethylammonium hydroxide n-Dodecyldimethylcyclohexylammonium hydrox ide n-Dodecyltrimethylammonium hydroxide n-Octadecylbenzyldimethylammonium hydroxide n-Dddecylphenyldimethylammonium hydroxide The nitrogenous bases free from negative groups and hydroxyl groups which may be used in practicing this invention are further characterized in that they have an association exponent (pkab) of about 5.00 to about 12.00 and preferably from 9.0 to about 11.40.

The proportions of the components of the reducing solutions may be varied considerably. For instance, the amount of arylene-diamino developing agent may vary from 2m 12 grams per liter with good results. The amount of alkali metal or ammonium sulfite may vary from 5 to 25 grams per liter of solution. The amount of weak alkali, e. g. sodium carbonate may vary from 0 to 30 grams per liter. With regard to the nitrogenous base free from negative groups and hydroxyl groups it may vary from 8 to 30 grams or ccs. per litter of solution.

The numerous advantages of this invention should be apparent to those skilled in the art. The reversal methods hereof represent a definite improvement over the art in that the residual silver image does not need to be removed. The reversal system involves only 8 steps and produces black images. Prior reversal processes involving the use of sodium hydrosulfite have various shortcomings and do not produce black images.

A further advantage is concerned with the fact that due to its energetic dye-producing action, the density of dye images is considerably greater, per density of silver produced than with ordinary color-forming developers. This means the amount of silver halides in the emulsion can be materially reduced resulting in an economical manufacturing improvement over films for ordinary reversal methods. This economy feature is borne out by the above examples. The coating weight of negative films for reversal processes is usually about 105 to 115 mgs., that is this amount of dried gelatino-silver halide emulsion covers 100 square centimeters. By the present invention coating weights of 80 mgs. are practical.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not to be limited to the specific embodiments herein except as defined by the appended claims.

I claim:

1. A photographic reversal process comprising developing a photographic element containing a latent image in silver halides in an ordinary developer to produce a negative image and develop ing the residual silver halide image without reexposure in the presence of a black color former with an aqueous reducing solution containing a compound of the general formula:

wherein R and R are members or the group consisting of hydrogen and alkyl radicals of 1 to 4 carbon atoms, and the water soluble salts thereof, and an aliphatic amine or 1 to 8 carbon atoms in an amount suflicient to change the characteristics of the solution so that it no longer distinguishes between exposed and unexposed silver salts, said amount being within the range from 8 ccs. to 30 grams per liter of solution; said base being free from negative groups and hydroxyl groups attached to carbon.

2. A photographic reversal process which comprises developing a photographic element containing at least one latent image layer in silver halides in an ordinary developer to produce a negative image and developing the residual silver halide image without re-exposure in the presence of a black color former with an aqueous reducing solution containing as the sole type or reducing agent at least one primary aromatic polyamino color developing agent, and an aliphatic amine of 1-6 carbon atoms in an amount suillcient to change the characteristics 01 the solution so that it no longer distinguishes between exposed and unexposed silver salts, said amount being within the range of from 8 cc. to 30 grams per liter of the solution, said amine being free from negative groups and hydroxyl groups attached to carbon.

3. A photographic reversal process which comprises developing a photographic element containing at least one latent image layer in silver halides in an ordinary developer to produce a negative-image and developing the residual silver halide image without re-exposure in the presence of a black color former with an aqueous reducing solution containing as the sole type of reducing agent at least one primary aromatic polyamino color developing agent and hexamethylenediamine in an amount sufficient to change the characteristics of the solution 50 that it no longer distinguishes between exposed and unexposed silver salts. said amount being within the range of from 8 cc. to 30 grams per liter of solution.

4. A photographic reversal process which comprises developing a photographic element containing at least one latent image layer in silver halides in an ordinary developer to produce a negative image and developing the residual silver halide image without re-exposure in the presence of a black color former with an aqueous reducing solution containing as the sole type of reducing agent at least one primary aromatic polyamino color developing agent, and beta-dimethylaminoethylamine in an amount sufilcient to change the characteristics of the solution so that it no longer distinguishes between exposed and unexposed silver salts. said amount being within the range oi from '8 cc. to 30 grams per liter of solution.

5. A photographic reversal process comprising developing a photographic element containing a latent image in silver halides in an ordinary developer to produce a negative image and developing the residual silverhalide image without reexposure in the presence or a black color former with an aqueous reducing solution containing a compound of the general formula:

wherein R and R are members of the group consisting of hydrogen and alkyl radicals or 1 to 4 carbon atoms, andthe water soluble salts thereof, and hexamethylenediamine in an amount sumcient to change the characteristics of the solution so that it no longer distinguishes between exposed and unexposed silver salts, said amount being within the range of from 8 cc. to 30 grams per liter of solution.

EMERY MESCHTER. 

